Electrically insulating materials for centrifugal mirrors
Abstract
The centrifugal mirror confinement scheme incorporates supersonic rotation into a magnetic mirror device, which stabilizes and heats the plasma. This concept is under investigation in the Centrifugal Mirror Fusion Experiment (CMFX) at the University of Maryland. Plasma rotation is driven by an axial magnetic field and a radial electric field that lead to velocity drifts in the azimuthal direction. An electrically insulating material is required to prevent the applied voltage from shorting on the grounded chamber. Hexagonal boron nitride (hBN) is a promising candidate material for plasma-facing components in future centrifugal mirrors due to its exceptional thermal and electrical properties. However, its performance under intense particle and heat fluxes characteristic of the plasma edge in fusion devices remains largely unexplored. Computational modeling for ion- and neutron-material interactions was carried out with RustBCA and OpenMC, respectively, and predicts relatively good performance in comparison to other insulating materials. Material coupons were then exposed to plasma in PISCES-A at UCSD and CMFX. A load-locked sample feedthrough was constructed and installed on CMFX to test coupons. Two erosion mechanisms were identified -- sputtering and grain ejection -- both of which were more apparent in silicon carbide than hBN.
Cite
@article{arxiv.2506.14847,
title = {Electrically insulating materials for centrifugal mirrors},
author = {Nick R. Schwartz and Carlos A. Romero-Talamás and Marlene I. Patino and Daisuke Nishijima and Matthew J. Baldwin and Russel P. Doerner and Artur Perevalov and Nathan Eschbach and Zachary D. Short and John Cumings and Ian G. Abel and Brian L. Beaudoin and Timothy W. Koeth},
journal= {arXiv preprint arXiv:2506.14847},
year = {2025}
}